My twin brother and I used to wrestle and playfight all the time when we were little. Then, it must be karma or something, he suddenly started getting huge, while I of course did not. Now he's 6'5" (!), a solid foot taller than I am.
So, eventually I had to simply face the reality that there was no way I was going to win these wrestling matches any more. Does that suck? Absolutely. But even now that's I've been on T for 3 years, and work out, etc., etc. I'm still not as strong as he is, and never will be. No matter how big or strong you get, there's always someone bigger and stronger.
I "dealt" with it by just not wrestling with him any more. In retrospect I actually think that was a mistake. Yes, it sucked to lose and was frustrating, intensifying what you are feeling about hating my stupid little weakling body. But at least I occasionally did learn some things I could do, even against a much bigger / stronger guy. So I guess I see two different ways to deal with it: avoid it, if it causes too much dysphoria. Or, embrace it and try to learn what you can from it, but with the mindset and understanding that you will not always be successful any more. Having brothers is great actually, because you don't have to worry about them "reading" you, etc.